Wobble plate pump



April 18, 1961 G. A. WAHLMARK 2,980,025

WOBBLE PLATE PUMP Filed Sept. 22, 1958 Ira/$72237 Garzrzarfl MaiZmar/z WOBBLE PLATE PUNIP Gunnar A. Wahlmark, Rockford, Ill., assignor to Borgllliinrner Corporation, Chicago, Ill., a corporation of ms Filed Sept. 22, 1958, Ser. No. 762,626

4 Claims. (Cl. 103-38) The present invention relates generally to wobble plate type pumps employing a plurality of reciprocable pistons respectively actuated by means of a wobble plate in which the throw thereof is variable between maximum and minimum positions in order to vary the output of the pump.

In wobble plate pumps employing a plurality of reciprocable pistons it is common practice to utilize output pump pressure to move the wobble plate fromits position of maximum throw to its position of minimum or zero throw, in which latter position the pistons are no longer reciprocated and consequently are ineffective to pump any fluid. In such pumping arrangements, some means must be provided for moving the wobble plate somewhat ofi of its zero throw position toward its maximum throw position in order to enable the pump to again commence pumping fluid.

The principal object of the present invention is to provide means automatically etfective to move or bias the wobble plate away from its zero throw position in the event .that the pump output pressure drops to substantially zero when the wobble plate is in its zero throw position.

More particularly, the present invention is applicable to a wobble plate type pump wherein the pump drive shaft is provided with a diagonal slot at one end thereof and within which a wobble plate actuator is receivable in order to effect Wobbling action of the wobble plate upon rotation of the drive shaft. A spring biased member disposed within a lateral opening formedin the drive shaft communicates with the diagonal slot and cooperates with an opening formed in the end of the wobble plate actuator when the wobble plate is in or near its zero piston throw position in order to bias the wobble plate toward a position corresponding to maximum piston throw.

One of the principal advantagesof the present invention is its simplicity of construction, and another advantage resides in the fact that the mechanism is always ready to function but is nevertheless out of the way when its function is not required. In other words, all additional structure for returning the wobble plate toward its position of maximum throw is eliminated.

The foregoing objects and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the appended drawing which comprises an elevation sectional view illustrating the principal features of the invention.

Turning now to the drawing, the pump in which the present invention is particularly applicable comprises a main housing section 1 and an auxiliary housing section 2, the housing sections 1 and 2 being rigidly and sealingly interconnected by means of a plurality of bolts 3 which extend through openings 4, formed in housing section 2, into threaded openings 5 formed in housing section 1. The housing section 1 is provided with an internal annular groove 6 and a sealing ring 7 is disposed in this groove and adapted to be compressed between the housing sections 1 and 2 in order to effect a seal therebetween.

4 atent The housing section 1 is internally cylindrical bored, as indicated at 8 for the reception of a cylinder block 9. A pair of annular grooves 10 and 11 are formed in the housing section 1 for receiving a pair of sealing rings 12 and 13 for effectively sealing the housing section 1 with respect to the cylinder block 9. The cylinder block 9 preferably does not rotate although no means are disclosed in the drawing for retaining the same against rointo the casing section 1, at 19. The casing l is provided with an annular groove 20 for receiving a sealing ring a 21 effective to seal the retainer 18 relative to the casing 1. An annular seal retainer 22 is formed with a cylindrical flange 23 adapted to be received within the inner periphery of the retainer 18-and the two retainers 22 and 18 are held in fixed position relative to the casing portion 1 by means of a plurality of bolts 24 threaded intothe casing portion 1, as indicated at 25. The seal retainer 22 is provided with an annular peripheral groove 26 within which a sealing ring 27 is disposed and an inner annular groove 28 which encloses a sealing ring 29 for effecting a seal between the retainer 22 and a seal member 36. The seal member 3%) is formed with a substantially optically flat sealing face 31 which cooperates with a corresponding substantially optically fiat sealing face 32 The drive shaft 16 is internally splined, as at 37 to re-,

ceive a complementary externally splined driving shaft inorder for applying rotary motion to the shaft 16. The drive shaft 16 is provided at its right end, as viewed in the drawing, with an enlarged portion 38. The enlarged portion 38 is formed with an external annular recess 39 which forms the inner race for the centralizing roller bearings 15. The enlarged portion 38 is also provided with a cylindrical diagonal slot 40 which is disposed at an angle to the axis of rotation of the shaft 16. The cylindrical diagonal slot 40 is adapted to receive an actuator member 41 rotatably mounted about a reduced portion 42 of a wobble plate 43 by means of a plurality of rollerbearing members 44. The outer surface of the actuator member 41 is substantially spherical in shape and is of only slightly smaller dimensions than the internal diameter of the diagonal cylindrical slot 46, so that the actuator 41 may be received within the slot 40 in order that rotation of the shaft 16 will effect wobbling of the wobble plate 43.

The wobble plate 43 is pivotally mounted on a substantially spherical member 45, the latter being reciprocable axially on a fixed member 46 which is rigidly secured to casing portion 2 by means of a plurality of bolts 47. The spherical mounting member 45 is movable axially by means of a piston member 48 which is reciprocable within a cylindrical portion 49 of the member 46. An enlarged piston 50 is adapted to have pump output pressure applied thereto in order to move the spherical pivot 45 and wobble plate 43 axially to the left, as viewed in the drawing.- The wobble plate 43 is complementarily formed with a suban inwardly opening annular ring 55 formed in the wobble plate 43. Upon the application of fluid underpressure behind piston 56 the spherical member 45 and wobble plate 43 are moved to the left, thereby causing the acutator 41 to slide into the cylindrical diagonal slot 40 in shaft 16.

The wobble plate 4.3 is provided with a peripheral or ring gear member 54 formed with an outwardly extending abutmentring 55 thereon. The gear member 54. and abutment ring 55 are suitably secured to the wobble plate 4-3 by any desired means. The gear member 54 is adapted to mesh with a complementary ring gear member 56 carried by the housing portion 9 and the abutment ring 55 is adapted to engage a complementary abutment ring 57 also carried by the housing portion 9, both of which are held in place by suitable pins 55 and a stop ring 59. Upon rotation of shaft 16, the diagonal slot 40 and actuator 41 cause the wobble plate 43 to wobble around.

the spherical member 45 with the gear members 54 and 56 in mesh and abutment rings 55 and 57 engaging one another. Such action of the wobble plate 43 is effective to create a pumping action by means which will now be described.

The cylinder block 9 is provided with a plurality of cylinders 69 within which a like number of piston members 61 are reciprocable. Each of the piston members 61 is provided with a spherical ring 62 which is held in abutment with a shoulder 63 on the piston member 61 by means of a threaded nut 64 threaded onto the end of the piston member 61. A spherical ring sealing member 65 is loosely mounted within the groove 66 formed by the nut 64 and ring 62 and effects a substantial seal between the piston 61 and the inner periphery of the cylinder 68. The spherical seal ring 65 and the spherical ring 62 enables the necessary slight angular motion of the piston 61 within the cylinder 66 without breaking the seal therebetween, which is essential upon movement of the pistons in a reciprccatory manner by means of the action of wobble plate 43.

Each of the pistons 61 is formed at its other end with a shoulder 67 adapted to engage an abutment shoulder 68 disposed within suitable bearings 69 formed in the wobble plate 43. The abutment shoulder 68 is held in place by means of a stop ring 76 disposed within an annular groove formed around the openings 69. Upon rotation of shaft 16 and the consequent wobbling motion of the wobble plate 43, the pistons 61 are reciprocated within cylinders 69 in order to provide the necessary pumping action.

The cylinder block 9 is provided with an annular semitoroidal groove 71 which communicates with a fluid inlet ring 72 formed in casing section 1 and which fluid inlet ring 72 communicates with a fluid source or supply connected with inlet 73. The casing section 1 is also provided with an annular ring 74 which constitutes a fluid outlet.

A valve plate 75 of substantially conventional construction is formed with a flat annular surface 76 cooperable with a complementary flat annular surface formed around the cylinder block 9. The valve plate 75 is provided with a semi-toroidal ring or groove 77 which communicates with an annular groove 78 formed in the casing member 1. The casing member 1 is provided with a substantially flat surface 79 cooperable with the opposite surface 86 of valve plate 75 in order to enable sliding of the valve plate 75 while still maintaining a substantial seal therewith. In order to insure the seal between the casing section 1 and the valve plate75, a of annular sealing rings 81 and 82, both of which are spring pressed into engagement with the valve plate 75, are provided. A'plurality of slots 83 are provided in the cylinder. block 9 and respectivelyestablish communication 4. v 1 between the cylinders 60 and the semi-toroidal groove 77 in valve plate when the valve plate 75 is moved to a position in communication therewith. At other times, the flat surface 76 on valve plate 75 functions to close the slots 83. In the operation of the pump, upon rotation of the shaft 16, the valve plate 75 is caused to orbit slightly so as to successively establish communication between the cylinder slots 33 and the semi-toroidal groove 77 so as to, in turn, establish communication between the inlet 73 and the cylinders 60. Such communication between the slots 83 and the inlet 73 is established during sucking movement or movement to the right of the pistons 61 in the cylinders in order to draw fluid from the inlet 73 into the cylinders 66 by means of the pistons 61 when they reciprocate by means of the action of the wobble plate 43. Upon the other half of each revolution of the shaft 16, the pistons 61 are caused to pump, thus causing fluid behind the piston members to be exhausted from the cylinders 60. Under these conditions, the orbital movement of the valve plate 75 is such as to establish fluid communication between the grooves 83 and the outlet 7 4.

The outlet 74 is connected with the space behind piston 50 by means of a plurality of fluid passages 84, 85 and 86. Similarly, fluid under pressure is applied to an annular piston-like portion 87 of the spherical member 45 by means of fluid conduits 88 and 89. Thus, as the pressure of the fluid in the outlet 74 is built up, there is a. tendency for the pivot member 45 to move axially to the left from a position corresponding to maximum throw of pistons 61 toward a position wherein the wobble plate abutment ring 55 is nearer to abutment ring 57 throughout the entire peripheries thereof. Thus, the actual out put of the pump is decreased.

As the resistance to the flow of fluid from the outlet 74 builds up, the pressure of the fluid builds up and the wobble plate 43 is moved further and further to the left toward the dotted position 90 of the actuator 41 and eventually to a position where the abutment rings 55 and 57 are in abutment throughout the entire peripheries thereof. Under these conditions, the actuator 41 is not moved by the diagonal slot 40, as the wobble plate 43 is then concentric with the axis of the shaft 16 and consequent rotation of the shaft 16 has no effect upon the Wobble plate 43 or pistons 61.

If the pump is operated with the wobble plate 43 in its vertical position with the abutment rings 55 and 57 in engagement throughout the peripheries thereof, and the pressure of the fluid in the outlet 74 and cylinders 60 drops off to zero and it-is again desired to start pumping, it becomes essential to provide means for moving the Wobble plate from its position of zero piston throw toward its position corresponding to maximum piston throw. Such means will now be described.

The shaft 16 is provided with a lateral opening 91 ex, tending substantially through the shaft 16 except for a narrow closure portion 92 at one end of the opening 91. The opening 91 communicates with the diagonal slot 41) and is adapted to receive a cylindrically shaped member 93 therein. The cylindrically shaped member 93 is spring biased upwardly, as viewed in the figure, by means of a suitable compression spring 94. A pin 95 extending through a hole 96 in the cylindrically-shaped member 93 base head 97 projecting outwardly into the diagonal slot 40 in such a Way as to cooperate with a complementary opening 98 formed along the axis and in the head of the actuator 41. Thus, when the fluid pressure is sufliciently great to move the wobble plate 43 toward its position of zero piston throw, in order to bring the abutment rings 55 and 57 into engagement throughout their peripheries, and thereafter. the output pressureof the pump is lowered so that the fluid pressure behind pistons 61is insuflicient to move the wobble plate 43 from its zero piston throw position, the compression spring. 9-4 urges'the cylindricalmernber 93 upwardly and. the pin 97, in engagement with the actuator 41, tends to pivot the wobble plate 43 about the spherical member 45 in order to impart some throw to the pistons 61. Thus, the pump is enabled to commence pumping and thereafter the force behind the pistons 61 due to the resistance of the fluid in the cylinders to compression is effective to return the wobble plate 43 to its position of maximum piston throw until the outlet pressure 74 builds up sufliciently to move the wobble plate 43 to its position of zero piston throw.

Obviously, the present invention provides a simple and convenient means for returning the wobble plate 43 to a position wherein pumping motion is applied to the piston 51 upon rotation of the drive shaft 16. Such means comprises the spring biased projecting member 97 which cooperates with the opening 98 in the wobble plate actuator 41. It is contemplated that changes and modifications may be made in the present invention without departing from the spirit or scope thereof.

What is claimed is:

1. A pumping unit comprising, in combination, a casing including means defining a plurality of cylinders therein, a plurality of pistons reciprocable in the respective cylinders, a pivotal Wobbler operatively engaging the respective pistons for imparting reciprocation thereto for causing the pistons to respectively suck fluid into the cylinders and to discharge fluid under pressure from the cylinders, a drive shaft concentrically mounted with respect to said casing and formed with a diagonal Wobbler actuating slot in the end thereof, said wobbler including an actuator adapted to be disposed within said diagonal slot of said drive shaft sothat upon rotation of the drive shaft reciprocation is imparted to said pistons, means responsive to the pressure of the fluid discharged from said cylinders and normally biasing said actuator' Wobbler into said diagonal actuating slot and thereby decreasing the throw of said pistons and, in turn, the fluid output of the pump, said drive shaft including means defining a transverse opening therein, and a biasing member projecting from said transverse opening whereby to cooperate with said actuator so as to move the Wobbler away from the position corresponding to a position of zero piston throw for enabling the pumping unit to commence pumping fluid even though the output fluid pressure may have previously dropped off to zero with the Wobbler in a position corresponding to zero piston throw.

2. A wobble plate pump having a plurality of fluid pumping pistons, a pivotally mounted wobble plate for actuating said pistons, said wobble plate being movable axially between a'pair of limit positions corresponding respectively to maximum piston throw wherein a maximum of fluid is pumped and to zero piston throw wherein no fluid is pumped, fluid pressure responsive means for biasing said wobble plate towards zero piston throw position against the urging of fluid acting against the pistons, a drive shaft having a diagonal slot cooperable with said wobble plate for imparting wobbling movement to said wobble plate, and spring biased means carried by said drive shaft and projecting into said diagonal slot and cooperable with said wobble plate for biasing the wobble plate away from said zero piston throw position and toward said position of maximum piston throw.

3. A wobble plate pump having a plurality of fluid pumping pistons, a pivotally mounted wobble plate for therein and eflective upon rotation of the drive shaft' to impart a wobbling motion to said wobble plate, and a spring biased member projecting into said diagonal slot, and cooperable with said wobble plate actuator for biasing the wobble plate away from said zero piston throw position and toward said position of maximum piston throw.

4. A wobble plate pump having a plurality of fluid pumping pistons, a pivotally mounted wobbles plate for actuating said pistons, said wobble plate being movable axially between a pair of limit positions corresponding respectively to maximum piston throw wherein a maximum of fluid is pumped and to zero piston throw wherein no fluid is pumped, fluid pressure responsive means for biasing said wobble plate toward said zero piston throw position against the urging of fluid acting against the pistons, said wobble plate being provided with an actuator rotatably mounted thereon, a drive shaft having a diagonal slot at one end thereof for receiving said actuator therein and effective upon rotation to impart a wobbling motion to said wobble plate, said drive shaft including means defining a transverse opening therethrough and in communication with said diagonal slot, said actuator having an axial opening therein, and a spring biased member disposed in said transverse shaft opening and adapted to be received within the axial opening in said actuator for thereby biasing the wobble plate away from said zero piston throw position and toward said position of maximum piston throw.

References Cited in the file of this patent UNITED STATES PATENTS 

